U.S. patent application number 14/760513 was filed with the patent office on 2015-12-10 for stacker crane and method for operating same.
This patent application is currently assigned to MURATA MACHINERY, LTD.. The applicant listed for this patent is MURATA MACHINERY, LTD.. Invention is credited to Hiroshi TANAKA.
Application Number | 20150353281 14/760513 |
Document ID | / |
Family ID | 51390877 |
Filed Date | 2015-12-10 |
United States Patent
Application |
20150353281 |
Kind Code |
A1 |
TANAKA; Hiroshi |
December 10, 2015 |
STACKER CRANE AND METHOD FOR OPERATING SAME
Abstract
A stacker crane includes a lower carriage including a lower
drive wheel, a lower travel motor, and a support located apart from
the lower drive wheel; an upper carriage including an upper drive
wheel and an upper travel motor that drives the upper drive wheel;
and a mast fixed to the lower carriage, standing upward from the
lower carriage and connected to the upper carriage, and including a
transfer device capable of moving up and down. A displacement
mechanism that raises and lowers the support is provided on the
lower carriage between a grounded position supported by a lower
rail and a retracted position lifted off the lower rail. The
support is lowered to the grounded position when the stacker crane
is installed between the lower rail and the upper rail and when the
stacker crane is stopped for maintenance, and the support is raised
to the retracted position when the stacker crane is operated.
Inventors: |
TANAKA; Hiroshi;
(Inuyama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MURATA MACHINERY, LTD. |
Kyoto-shi, Kyoto |
|
JP |
|
|
Assignee: |
MURATA MACHINERY, LTD.
Kyoto-shi, Kyoto
JP
|
Family ID: |
51390877 |
Appl. No.: |
14/760513 |
Filed: |
December 18, 2013 |
PCT Filed: |
December 18, 2013 |
PCT NO: |
PCT/JP2013/083844 |
371 Date: |
July 13, 2015 |
Current U.S.
Class: |
187/240 |
Current CPC
Class: |
B65G 1/0407 20130101;
B66F 9/072 20130101 |
International
Class: |
B65G 1/04 20060101
B65G001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 20, 2013 |
JP |
2013-030987 |
Claims
1-10. (canceled)
11. A stacker crane, comprising: a lower carriage including a lower
drive wheel in contact with a lower rail, a lower travel motor that
drives the lower drive wheel, and a support located apart from the
lower drive wheel along a length direction of lower rail; an upper
carriage including an upper drive wheel in contact with an upper
rail, and an upper travel motor that drives the upper drive wheel;
and a mast fixed to the lower carriage, standing upward from the
lower carriage, connected to the upper carriage, and having a
transfer device attached movably up and down; wherein the lower
carriage is provided with a displacement mechanism that raises and
lowers the support between a grounded position supported by the
lower rail and a retracted position lifted upward off the lower
rail.
12. The stacker crane according to claim 11, wherein the lower
carriage includes a main body including the lower drive wheel and
the lower travel motor, and the support located either in front of
or behind the main body; and the displacement mechanism includes:
at least an eccentric pin including a circular plate, a round bar
including a base end that is integrated with the circular plate and
is eccentric relative to a center of the circular plate, a screw
portion provided at a leading end of the round bar, and a
manipulation portion that rotates the circular plate; at least a
receiving hole provided in the support for the circular plate or
the round bar; and at least a receiving hole provided in the main
body for the round bar or the circular plate.
13. The stacker crane according to claim 11, wherein the support
includes a roller in contact with an upper surface of the lower
rail at the grounded position and lifted off the lower rail at the
retracted position.
14. The stacker crane according to claim 13, wherein the support
includes at least a guide roller that faces a guide surface on an
underside of the lower rail, is at an opposite position to the
roller and is attached to the support with a gap between the guide
roller and the guide surface of the lower rail both at the grounded
position and at the retracted position.
15. The stacker crane according to claim 11, wherein, when the
support is grounded at the grounded position, along the length
direction of the lower rail, a center of gravity of the mast and a
position of contact between the lower drive wheel and the lower
rail are located at a same point.
16. The stacker crane according to claim 12, wherein the
displacement mechanism causes the support to move up and down with
respect to the main body between the retracted position and the
grounded position.
17. The stacker crane according to claim 16, wherein the
displacement mechanism is configured to make the mast perpendicular
to the main body when the stacker crane is installed between the
lower rail and the upper rail and also when the stacker crane is
stopped for maintenance.
18. The stacker crane according to claim 17, wherein at a position
along the length direction of the lower rail, the mast is fixed
directly above the lower drive wheel.
19. The stacker crane according to claim 18, wherein the support
includes at least a roller in contact with an upper surface of the
lower rail at the grounded position and lifted off the lower rail
at the retracted position, and a guide roller facing a guide
surface on an underside of the lower rail at an opposite position
to the roller; the guide roller is attached to the support with a
gap between the guide roller and the guide surface of the lower
rail both at the grounded position and at the retracted position;
neither the roller nor the guide roller comes into contact with the
lower rail when tilting of the mast to the lower carriage is within
an allowable range; and if the tilting of the mast to the lower
carriage exceeds the allowable range, the roller or the guide
roller comes into contact with the lower rail.
20. A method for operating a stacker crane according to claim 11,
the method comprising: lowering the support to the grounded
position supported by the lower rail when the stacker crane is
installed between the lower rail and the upper rail and when the
stacker crane is stopped to perform maintenance; and raising the
support to the retracted position lifted off the lower rail when
operating the stacker crane.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a stacker crane and a
method for operating the same, and in particular relates to
reducing stress between a mast and a lower frame.
[0003] 2. Description of the Related Art
[0004] The applicant has proposed providing travel motors in upper
and lower carriages of a stacker crane so as to cause the upper and
lower carriages to travel in a synchronized manner (See, for
example, JP 2002-106414A). If the upper and lower carriages run out
of synchronization, a strong force is exerted on the connection
between the mast and the carriages, and therefore, in JP
2002-106414A, the mast is attached pivotally to the lower
carriage.
[0005] However, a pivotal mast is difficult to stand upright during
installation of the stacker crane. Similarly, if the mast does not
stand upright, it is difficult to perform maintenance on the
stacker crane. Furthermore, if a mast with a large weight is to be
pivoted, a large pivoting mechanism is needed.
SUMMARY OF THE INVENTION
[0006] Preferred embodiments of the present invention provide a
stacker crane with a simple structure that significantly reduces
stress exerted on a connection between a mast and a lower carriage
during normal traveling, while the mast is stood upright during
installation and maintenance of the stacker crane.
[0007] A stacker crane according to a preferred embodiment of the
present invention includes a lower carriage including a lower drive
wheel in contact with a lower rail, a lower travel motor that
drives the lower drive wheel, and a support located apart from the
lower drive wheel along a length direction of lower rail; an upper
carriage including an upper drive wheel in contact with an upper
rail, and an upper travel motor that drives the upper drive wheel;
and a mast fixed to the lower carriage, standing upward from the
lower carriage, connected to the upper carriage, and having a
transfer device attached so as to be capable of being elevated,
wherein the lower carriage is provided with a displacement
mechanism that raises and lowers the support between a grounded
position supported by the lower rail and a retracted position
lifted upward off the lower rail.
[0008] In a method for operating a stacker crane according to
another preferred embodiment of the present invention, the support
is lowered to the grounded position and supported by the lower
rail, when the stacker crane is installed between the lower rail
and the upper rail and also when the stacker crane is stopped so as
to perform maintenance, and the support is raised to the retracted
position lifted upward off the lower rail when the stacker crane is
operated.
[0009] A state is considered in which the upper carriage and the
lower carriage run out of synchronized travel and the mast tilts
from a perpendicular state. Here, if the support is in contact with
the lower rail, a strong force is exerted on the connection between
the mast and the lower carriage, and therefore high rigidity is
required at the connection. By contrast, if the support is allowed
to be raised and lowered between a grounded position and a
retracted position and further, the support is retracted during
operation of the stacker crane, or in other words, during normal
operations excluding maintenance, testing, or the like, the strong
force is not exerted on the connection if the mast tilts within an
allowable range. As a result, the weight of the mast and the lower
carriage is reduced, and the durability and reliability thereof are
increased. Also, if the support is operated during installation of
the stacker crane, during maintenance, and the like, the
orientation of the lower carriage is stabilized, and the mast
stands upright perpendicularly. Accordingly, the stacker crane is
installed accurately and easily, and maintenance is also easier.
Furthermore, since the mast may be fixed to the lower carriage, the
structure of the stacker crane is simpler compared to the case
where the mast is able to pivot with respect to the lower
carriage.
[0010] Preferably, the lower carriage includes a main body
including the lower drive wheel and the lower travel motor, and the
support located either in front of or behind the main body, and the
displacement mechanism includes at least an eccentric pin including
a circular plate, a round bar including a base end that is
integrated with the circular plate and is eccentric relative to the
center of the circular plate, a screw portion provided at a leading
end of the round bar, and a manipulation portion that rotates the
circular plate, at least a receiving hole provided in the support
for the circular plate or the round bar, and at least a receiving
hole provided in the main body for the round bar or the circular
plate. Thus, the support may be raised and lowered between the
grounded position and the retracted position by rotating the
eccentric pin with the manipulation portion.
[0011] A mechanism may be used in which a bottom surface of the
support is directly in contact with the lower rail, but preferably,
the support includes a roller that comes into contact with an upper
surface of the lower rail at the grounded position and is lifted
off the lower rail at the retracted position. Thus, not only is the
mast kept upright by the support at the grounded position, but the
stacker crane is easily moved by a manual push or the like during
installation and during maintenance.
[0012] Preferably, the support includes at least a guide roller
that faces a guide surface on an underside of the lower rail, is at
an opposite position to the roller and is attached to the support
with a gap between the guide roller and the guide surface of the
lower rail both at the grounded position and at the retracted
position. Thus, if the mast tilts toward the support beyond the
allowable range, the roller will come into contact with the lower
rail to prevent further tilting. Also, if the mast tilts toward the
side opposite to the support beyond the allowable range, the guide
roller will come into contact with the guide surface of the lower
rail to prevent further tilting.
[0013] Preferably, when the support is grounded at the grounded
position, along the length direction of the lower rail, the center
of gravity of the mast and the position of contact between the
lower drive wheel and the lower rail are the same. If the support
is lowered to the grounded position, the weight from the mast is
exerted directly on the point of contact between the drive wheel
and the lower rail, and the mast stands upright perpendicularly. If
two or more drive wheels are provided and are in contact with two
or more lower rails, the center of gravity of the mast is
preferably positioned on a line connecting the points of contact
between the drive wheels and the lower rails.
[0014] Preferably, the displacement mechanism makes the support up
and down with respect to the main body between the retracted
position and the grounded position.
[0015] More preferably, the displacement mechanism is configured to
make the mast perpendicular to the main body when the stacker crane
is installed between the lower rail and the upper rail and also
when the stacker crane is stopped to perform maintenance. This
configuration makes it easier to perform installation and
maintenance of the stacker crane. Also, if the support is
retracted, operation of the stacker crane may be started from a
state in which the mast is perpendicular to the lower carriage.
Since the mast is perpendicular to the lower carriage, a moment of
force that causes the mast to tilt is less likely to act
thereon.
[0016] In particular, it is preferable that at a position along the
length direction of the lower rail, the mast is fixed directly
above the lower drive wheel. Thus, the weight from the mast is
exerted directly on the point of contact between the lower drive
wheel and the travel rail, and a moment of force that causes the
mast to tilt is less likely to act thereon.
[0017] Most preferably, the support includes at least a roller in
contact with an upper surface of the lower rail at the grounded
position and lifted off the lower rail at the retracted position,
and a guide roller facing the guide surface on the underside of the
lower rail at an opposite position to the roller, the guide roller
is attached to the support with a gap between the guide roller and
the guide surface of the lower rail both at the grounded position
and at the retracted position, neither the roller nor the guide
roller comes into contact with the lower rail when tilting of the
mast to the lower carriage is within the allowable range, and if
the tilting of the mast to the lower carriage exceeds the allowable
range, the roller or the guide roller comes into contact with the
lower rail.
[0018] Thus, at the retracted position, the stacker crane may be
moved by a manual push or the like with the roller. During
operation of the stacker crane, even if the mast tilts within the
allowable range due to the upper and lower carriages running out of
synchronization for some reason, a strong force is not exerted on
the connection between the mast and the lower carriage.
Accordingly, the durability and reliability of the connection are
improved, and the weight of the connection is reduced. Also, if the
mast tilts beyond the allowable range, the roller comes into
contact with the lower rail to prevent further tilting. Also, if
the mast tilts beyond the allowable range in the opposite
direction, the guide roller comes into contact with the guide
surface of the lower rail to prevent further tilting.
[0019] The above and other elements, features, steps,
characteristics and advantages of the present invention will become
more apparent from the following detailed description of the
preferred embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a partial cutout side view of a stacker crane and
upper and lower travel rails according to a preferred embodiment of
the present invention.
[0021] FIG. 2 is a cross-sectional view taken along line A-A in
FIG. 1.
[0022] FIG. 3 is an enlarged cross-sectional view taken along line
B-B in FIG. 1.
[0023] FIG. 4 is a diagram showing a structure for attaching an
eccentric pin.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Hereinafter, preferred embodiments of the present invention
will be described. The scope of the present invention should be
construed based on the description of the claims and in accordance
with the understanding of a person skilled in the art, with
reference to the description of the specification and known
techniques in the field.
[0025] FIGS. 1 to 4 show a stacker crane 2 according to a preferred
embodiment of the present invention. In the drawings, reference
numeral 4 indicates a lower carriage including a main body 5 and a
support 28, reference numeral 6 indicates an upper carriage, and a
mast 8 fixed to the lower carriage 4 connects the upper and lower
carriages 4 and 6. The mast 8 may be fixed to the upper carriage 6
or be attached pivotally to the upper carriage 6. The mast 8 may be
a perpendicular tube that raises and lowers a transfer device 10
such as a SCARA arm, and instead of directly raising and lowering
the transfer device 10, the mast 8 may raise and lower an elevating
platform on which a transfer device is mounted. Reference numeral
11 indicates a transfer motor that drives the transfer device
10.
[0026] The stacker crane 2 travels inside of an automated warehouse
(not shown) or the like, the lower carriage 4 travels along a lower
rail 12, and the upper carriage 6 travels along an upper rail 14.
The upper surface of the lower rail 12 is a tread 16, the underside
surface thereof is a guide surface 18, and reference numeral 20
indicates a side surface thereof. One drive wheel 22 and a travel
motor 24 therefor are provided in the main body 5 of the lower
carriage 4, for example. The support 28 is attached to the bridge
26 of the main body 5 and may be raised and lowered between a
grounded position and a retracted position. In the grounded state,
the support 28 is supported in contact with the tread 16 of the
lower rail 12. In the retracted position, the support 28 is lifted
and is not in contact with the tread 16 of the lower rail 12.
[0027] The support 28 includes one driven roller 30, for example.
The main body 5 and the support 28 respectively include guide
rollers 32 and 33 that face the guide surface 18, and guide rollers
34 and 35 that are guided by the side surface 20. The guide rollers
32 to 35 are provided in pairs on both the left and right of the
lower rail 12, and the guide rollers 33 are separated from the
guide surface 18 by a gap, when the support is at the grounded
position and also when it is at the retracted position. When the
mast 8 tilts forward beyond an allowable range, the guide rollers
33 come into contact with the guide surface 18 to restrict forward
tilting. In the present specification, the left and right direction
is the direction orthogonal or substantially orthogonal to the
lower rail 12 or the upper rail 14 in a horizontal plane, and
regarding front and rear, the main body 5 is in the front and the
support 28 is in the rear.
[0028] As shown in FIG. 3, the guide rollers 33 are attached to the
support 28 by bearings 37, and the guide rollers 35 are attached to
the support 28 by bearings 36. The guide rollers 32, 34, and 35 may
always be in contact with the lower rail 12, or may be configured
to come into contact with the lower rail 12 when the mast 8 tilts
left or right beyond the allowable range.
[0029] Returning to FIG. 1, a pair of left and right drive wheels
40 are provided on the upper carriage 6, for example, are driven by
an upper travel motor 41 to travel, and are in contact with the
side surface of the upper rail 14. Also, for example, a pair of
left and right guide rollers 42 are provided on the upper carriage
6 to guide the upper carriage 6 so that it does not shake left and
right with respect to the upper rail 14. Further, sprockets, gears,
or the like are provided inside of the upper carriage 6 in addition
to the drive motor 41 for the chain or belt to raise and lower the
transfer device 10. The upper carriage 6 may have any
configuration.
[0030] FIG. 2 shows the structure of the lower carriage 4. An
elevation motor 44 that raises and lowers the transfer device 10 is
arranged to face the travel motor 24. Also, the center of gravity
of the mast 8 is located directly above the drive wheel 22, and if
the mast 8 is stood upright perpendicularly by the support 28, the
center of gravity of the mast 8 will be the same to the position of
contact between the drive wheel 22 and the lower rail 12, or in
other words, the support will be directly above the center of the
drive wheel 22 in the length direction. The main body 5 includes a
pair of left and right bridges 26 and 26, and between the bridges
26 and 26 the transfer motor 11 and the transfer device 10 are
accommodated when the transfer device 10 is lowered.
[0031] As shown in FIGS. 3 and 4, the driven roller 30 is arranged
in the center in the left-right direction of the support 28, and is
supported by a pair of bearings 46 and 46. For example, an
attachment plate 48 on the support 28 is fixed by bolts 56 to an
attachment plate 49 on the bridge 26, and is configured such that
its height can be adjusted with eccentric pins 50. The eccentric
pins 50 each include a circular plate 51 and a round bar 58 on the
support 28, the center line C-C of the round bar 58 is eccentric
from the center line D-D of the circular plate 51, and the center
of an manipulation portion 52 such as a hexagonal hole is the same
to the center line C-C. Further, the manipulation portion may be of
any shape such as a nut shape instead of the hexagonal hole, and it
is sufficient that the manipulation portion rotates the eccentric
pin 50 according to a manual operation. A screw portion 60 is
provided on the leading end of the round bar 58, the circular plate
51 is accommodated in a hole 53 of the attachment plate 48, the
round bar 58 is accommodated in a round hole 59 of the attachment
plate 49 and the screw portion 48 is fixed by the nut 62, such that
the eccentric pin 50 is prevented from rotating. As shown in FIG.
3, the hole 53 has a shape slightly different from a circle so that
the circular plate 51 may rotate around the manipulation portion
52. In the present preferred embodiment, the manipulation portion
52 preferably is provided on the support 28, but the eccentric pin
50 may be arranged such that the manipulation portion 52 is located
on the bridge 26. Also, the eccentric pin 50 is a member that
includes an axis on the attachment plate 48 and an axis on the
attachment plate 49 and is able to be rotated by operating the
manipulation portion 52.
[0032] The manipulation portion 52 is rotated with a hexagonal
wrench or the like, and for example, the eccentric pin 50 is
rotated about the axis C-C, and the support 28 is raised and
lowered by about several millimeters with respect to the main body
5, for example. The example of FIG. 3 shows a grounded state
(grounded position) in which the driven roller 30 is in contact
with the lower rail 12. If the manipulation portion 52 is rotated
from this state, a retracted state (retracted position) will be
entered in which the driven roller 30 is lifted off the lower rail
12. The gap between the driven roller 30 and the lower rail 12 in
the retracted state determines the allowable range with respect to
rearward tilting of the mast 8. In the retracted state, the support
28 rises and the driven roller 30 is lifted from the lower rail 12.
In the grounded state, the support 28 lowers and the driven roller
30 comes into contact with the lower rail 12. Also, the bolts 56
are inserted into a long holes 54 to adjust the height of the
support 28 with the eccentric pin 50, and by fastening the bolts 56
at that position, the height of the support 28 may be fixed.
[0033] An operation of the present preferred embodiment will be
described next. When the stacker crane 2 is installed between the
lower rail 12 and the upper rail 14 in an automated warehouse, it
is brought into the grounded state by lowering the support 28. At
this time, the height of the support 28 is adjusted so that the
mast 8 is perpendicular. Upon doing so, the stacker crane 2 may be
installed, keeping the mast 8 in the perpendicular state, and since
the orientation of the lower carriage 4 is stable, installation is
easier. Also, at a time of performing maintenance, if the
orientation of the lower carriage 4 is stabilized so that the mast
8 is kept in the perpendicular state, the task is easier.
Furthermore, the stacker crane 2 may be moved by pushing manually
or the like when installing and when performing maintenance. It is
difficult to move the stacker crane 2 by pushing manually, when the
support is in the retracted state, because the orientation of the
lower carriage 4 is unstable and the mast 8 does not stand on its
own.
[0034] During normal operation of the stacker crane 2, the support
28 is raised so that the driven roller 30 is lifted off the lower
rail 12. Even if the upper and lower carriages 4 and 6 come out of
synchronization and the mast 8 tilts rearward within the allowable
range, a strong force is not exerted on the connection between the
mast 8 and the lower carriage 4. Accordingly, the durability and
reliability of the connection are improved, and the weight of the
connection portion is reduced.
[0035] If the mast 8 tilts rearward beyond the allowable range, the
driven roller 30 comes into contact with the lower rail 12 and
further rearward tilting is prevented. Also, if the mast 8 tilts
forward beyond the allowable range, the guide roller 33 comes into
contact with the guide surface 18 of the lower rail 12 and further
forward tilting is prevented.
[0036] The center of gravity of the mast 8 in the grounded state is
located directly above the center of the drive wheel 22. Therefore,
the weight from the mast 8 is exerted directly on the point of
contact between the drive wheel 22 and the lower rail 12, and there
is no moment of force that causes the mast 8 to tilt.
[0037] While preferred embodiments of the present invention have
been described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the present invention. The
scope of the present invention, therefore, is to be determined
solely by the following claims.
* * * * *